Co-doped zinc oxide nanoparticles embedded in Polyvinylalcohol Hydrogel as solar light derived photocatalyst disinfection and removal of coloured pollutants

• In the polyvinyl alcohol hydrogel, co-doped ZnO NPs were created using coprecipitation. • Co-doped ZnO NPs embedded in PVA hydrogel degraded dye completely in 48 min under solar light. • 12% Co-doped ZnO NPs embedded in PVA hydrogel showed good cyclic stability and antimicrobial activities. In this study Co doped ZnO NPs (CoZnO) were synthesized by using polyvinyl alcohol hydrogel (PVA HG) as platform for methyl orange dye (MO) degradation. CoZnO/PVA photocatalysts are not only effective to degrade organic pollutants but also used for disinfection the water. Co-doped zinc oxide nanoparticles (CoZnO NPs) as an excellent photocatalyst were synthesized by the coprecipitation method. ZnO NPs due to its large band gap is only UV light mediated photocatalyst which is only 4% of solar spectrum. In order to fully utilize of solar spectrum, low cast Co transition metal was doped to ZnO NPs to make is visible light derived photocatalyst by lowering its band gap. A high adsorption power of PVA HG enhance photocatalyst activity. For this purpose, Polyvinyl alcohol hydrogel was used along with Co doped ZnO NPs to enhance the photocatalytic activity. Polyvinyl alcohol hydrogel (PVA HG) was prepared by basic hydrolysis of polyvinyl acetate gel which was prepared by free radical emulsion method using diacrylate crosslinker. Co-doped ZnO NPs were formed in the PVA HG matrix by coprecipitation method. The doping concentration of Co was changed from 0-16%(w/w). and optimized for best photocatalytic ability. The 12% Co-doped ZnO NPs showed best photocatalytic ability. So, 12CoZnO NPs were incorporated in the PVAHG for dye degradation and disinfection study. The 12CoZnO/PVA yielded composite showed an extreme rise in photocatalytic efficiency and completely mineralized MO in 48 minutes. The prepared composite showed better degradation of methylene blue than 12CoZnO NPs under UV-vis light radiation. The stability of PVA/CoZnO NC for photodegradation of dye was verified by a recycling experiment of the composite.